In the past, dentures have been made to closely resemble the size and shape of natural teeth. Unlike natural teeth, however, dentures are not permanently secured to the denture wearer's jaw. As a result, dentures designed to look and function like natural teeth do not have the inherent stability of natural teeth.
In particular, lateral movement of the lower jaw relative to the upper jaw is more easily accommodated in natural teeth because of the permanent attachment of the teeth to the lower jaw. During mastication with natural teeth, the central fossa of the lower molars cooperates with the functional cusp of opposing upper molars in a mortar and pestle-like action. When these shapes are copied into artificial dentures, the lower teeth tend to move, tip, or otherwise dislodge as the functional cusp of the upper molars slides outward toward the buccal side of the lower molars.
Protrusive movement of the lower jaw can also be problematical for denture wearers. Especially when the multiple ridges and troughs of natural teeth are formed in the artificial teeth of dentures, blocking or tripping of opposing teeth is often experienced during protrusive movement of the lower jaw.
Unexpected movement of dentures, such as the sliding, tipping, tripping, blocking and dislodging described above, creates serious problems for denture wearers. For example, denture wearers sometimes avoid the company of others because of embarrassment relating to removal of their dentures or lack of control over their dentures. Also by way of example, sore spots may develop on the gums of denture wearers as a result of non-uniform pressure points and/or uncontrolled denture movement. Once sore spots develop, they are further aggravated by denture movement. To minimize pain from these sore spots denture wearers sometimes avoid eating certain foods, creating dietary imbalances and other health problems. The existence of sore spots and continued discomfort may also cause denture wearers to remove their dentures for extended periods of time. When dentures are worn erratically, the original fit of the denture can be lost, in part because of the shrinkage of the wearer's gums. Once the original fit is lost, the incidence and extent of sore spots increase, with the fit of the dentures deteriorating steadily further.
Even when the chewing surfaces of artificial teeth of dentures are not made to look like natural teeth, dental professionals can find it difficult to achieve a satisfactory fit with new dentures. The more complex the shape of artificial dentures, the more difficult such dentures are to fit to a patient. Even after multiple adjustment appointments with the dental professional, malocclusion problems persist in upwards of 85-90% of new denture wearers. Whether or not malocclusion problems are solved, the need for multiple adjustment appointments increases significantly the cost of fitting dentures.
When upper and lower dentures meet in a chewing motion, opposing force is applied to each of the upper and lower dentures. Because the lower denture of a full mouth denture set contacts approximately one-third the gum surface area as compared to the gum surface area contacted by the opposing upper denture of a full mouth denture set, approximately three times the pressure is placed on the lower jaw as compared to the pressure placed on the upper jaw. This increased pressure on the lower denture and jaw creates sore spots and causes undesired movement of the lower denture, in part because of the inability of the surface tension created by saliva between the gum and lower denture to maintain the lower denture in position.
To increase denture stability, some dental professionals align the artificial teeth of lower dentures to the lingual side of the crest of the ridge of the lower jaw or mandible. While this alignment may lend increased stability to the lower denture, the tongue of the denture wearer can become crimped, leading to speech problems and eating difficulties. To avoid these problems, other dental professionals align the artificial teeth of lower dentures to the buccal side of the apex of the mandibular ridge. However, in this alignment the lower denture remains susceptible to tipping and dislodging when pressure is selectively applied near the buccal edge of the chewing surface of the lower molars. Because of this susceptibility to tipping and dislodging, buccal side alignment may require substantial occlusal adjustments to obtain a satisfactory fit.
Dentures typically demonstrate approximately 40% of the biting and chewing efficiency of natural teeth. To compensate for this decreased efficiency, dentures have been made wholly or partially of metal. Metal has been found to be particularly useful in providing a hardened cutting edge to increase cutting efficiency. However, the metal components are often embedded in dentures in complex patterns, making such dentures expensive to manufacture. These complex designs are susceptible to trapping food during mastication. In addition, the more complex metal cutting edge patterns can require increased training of the dental professional to learn how to correctly install such dentures. Even with additional training, multiple occlusal adjustments may be required to achieve a satisfactory fit with such dentures.
In other metal dentures, a metal insert or frame substitutes for porcelain or other life-like artificial teeth. Such metal inserts present obvious cosmetic problems. In addition, exposed, sharpened cutting edges of such metal inserts can injure the tongue and cheek of the denture wearer. To date, metal dentures have failed to completely solve the many problems facing denture wearers.
It is against this background that the significant improvements and advancement of the present invention have taken place in the field of dentures.